Chemistry isn’t acting alone in gene expression

By sonyamcd
Jan 28, 2010

Loop

University of Michigan Biophysics researchers have shown that slight forces on DNA molecules could play a role in gene expression---the process at the heart of biological function that tells a cell what to do.

Using custom “optical tweezers,” or lasers, the scientists tugged on the ends of E. coli DNA strands with 200-femtonewton forces approximating the weight of one-billionth of a grain of rice, said Yih-Fan Chen, a doctoral student in the Department of Biomedical Engineering. Chen designed and built the tweezers.

In the captive DNA threads, the scientists observed a 10-fold decrease in the rate at which the strands looped in on themselves.

DNA looping prevents genes within the loops from being expressed. A common mechanism for gene regulation, it also occurs in complex organisms including humans. Specialized proteins act as buckles to connect points on the DNA to form the loops.